One of the most active areas in cancer research is the field of proteolytic enzymes and their role in the spread of cancer. One such class of protease that plays a significant role in the progression of cancer are the serine proteases, in particular Urokinase-type plasminogen activator (uPA). Inhibitors of uPA have been postulated to be of therapeutic value in treating cancer. Inhibitors of these serine proteases also tend to be inhibitors of the closely related blood-clotting enzymes. One such blood-clotting enzyme is Factor Xa.
Factor Xa (herein after “FXa”), the converting enzyme of pro-thrombin to thrombin, has emerged as an alternative (to thrombin) target for drug discovery for thromboembolic disorders. A variety of compounds have been developed as potential FXa inhibitors.
Kunitada and Nagahara in Current Pharmaceutical Design, 1996, Vol. 2, No.5, report amidinobenzyl compounds as FXa and thrombin inhibitors. Disclosed in U.S. Pat. No. 5,576,343 are aromatic amidine derivatives and salts thereof, as reversible inhibitors of FXa. These compounds comprise amidino substituted indolyl, benzofuranyl, benzothienyl, benzimidazolyl, benzoxazoyl, benzothiazolyl, naphthyl, tetrahydronaphthyl and indanyl groups, attached to a substituted phenyl ring by an alkylene group having from 1 to 4 carbon atoms.
In spite of the above discussed efforts, desirable treatment of cancer and thromboembolic disorders still remains elusive. There is thus a need for new compounds that will be effective in inhibiting serine proteases, such as Urokinase, and blood-clotting enzymes such as FXa. Keeping these needs in mind, the present invention provides novel inhibitors as discussed below.